Amine activated polymerization process



Patented June 19, 1951 AMINE ACTIVATED POLYMERIZATION raocrss George E. Serniuk, Roselle,- N. J., asslgnor to Standard Oil Development Company, a combration of Delaware No Drawing. Original application December 30,

1944, Serial No. 570,747. Divided and this application June 7, 1950, Serial No. 166,760

1 Claim.

This invention pertains to the manufacture of synthetic rubber-like materials and in particular to the preparation of such materials by the polymerization of certain unsaturated materials in aqueous emulsion. This application is a division of Serial No. 570,747 filed December 30, 1944, now U. S. Patent No. 2,529,315.

Synthetic rubber-like materials have been prepared by polymerizing one or more conjugated diolefins or by interpolymerizing one or more conjugated diolefins with copolymerizable materials containing a single C=C group such as styrene, substituted styrenes, acrylonitrile, methacrylonitrile, acrylic acid esters, unsaturated ketones and the like in aqueous emulsion, using a compound capable of liberating oxygen under the reaction conditions such as hydrogen peroxide, benzoyl peroxide and alkali metal or ammonium persulfates and perborates as catalysts.

As ordinarily carried out, the reactants are emulsified in from an equal to a two-fold quantity of water using as the emulsifier water-soluble soaps such as the alkali metal or ammonium oleates and stearates as well as various surface active agents such as salts of alkylated naphthalene sulfonic acids, salts of aliphatic and olefinic sulfonic acids, salts of fatty alcohol sulfuric acid esters and also acid addition salts of high molecular weight alkyl amines. A polymerization catalyst such as potassium persulfate and preferably a suitable polymerization modifier is added and the mixture maintained under agitation at temperatures of from about 20-60 C. for a period sufiicient to permit at least about 70% of the monomer materials to become converted to a high molecular weight polymer. The polymers formed Vary from hard, resinous materials to soft, rubber-like materials depending upon the particular monomers and th proportions in which they are used and the reaction conditions applied. In general, soft rubbery polymers result when the diolefin is the preponderant polymerizable material, provided, of course, that other reaction conditions are right.

In the polymerization or copolymerization of conjugated diolefin hydrocarbons in aqueous emulsion the reaction times have been found to be rather long to reach approximately 70-75% conversion of the monomeric materials used when using reaction temperatures in the range of 25-40 C. Attempts have been made to speed up the rate of reaction as by raising the temperature 'at which the reaction is conducted, but this, in general, has resulted in inferior polymerizates. Certain materials which have a modifying effect upon the polymerization to give more plastic polymers also have a promoting eflect. Such materials include primary, secondary and tertiary alkyl and aralkyl mercaptans used preferably in the presence of a peroxide or per-salt. (Certain promoters such as carbon bisulfide, aldehydes, oxides and salts of polyvalent metals have been proposed but use of such materials has not made possible the desired rates of reaction in the temperature range of about 20-40 C.) The most generally used polymerization modifiers are the aliphatic mercaptans containing more than six and preferably about twelve carbon atoms per molecule. Although these mercaptans promote or increase the speed of reaction as well as cause the formation of more plastic polymers, there is still a demand for other and improved types of promoting agents.

It is the object of this invention to provide the art with a novel method of activating emulsion polymerization reactions.

It is also the object of this invention to activate the emulsion polymerization of conjugated diolefins or of mixtures of conjugated diolefins with certain copolymerizable compounds without detrimentally affecting the polymer product quality.

It is also an object of this invention to provide a new class of compounds which act as polymerization promoters and which can also be used in conjunction with known types of promoters and modifiers in the emulsion polymerization of conjugated diolefins or active monoolefins of the vinyl type, or of mixtures of conjugated diolefins with certain unsaturated compounds which are copolymerizable with conjugated diolefins.

These and other objects will appear more clearly from the detailed specification and claims which follow.

It has now been found that the production of synthetic rubber-like material by the emulsion polymerization of conjugated diolefins, or mixtures of conjugated diolefins with certain copolymerizable compounds takes place at a much faster rate and/or at lower temperatures without injury to the product quality if an amino compound such as water-soluble, primary, secondary, tertiary amines and polyamines, preferably aliphatic, alicyclic or heterocyclic amines and derivatives such as hydroxy amines wherein the OH group is attached to a carbon atom, amino ethers, salts of amines uch as hydrochloride, sulfates, etc, chloro amines and the like are used in low concentrations in the reaction mixtures.

My invention is applicable to the production of C=C linkage such as acrylonitrile, methacrylonitrile, acrylic acid esters such as methyl acrylate and methyl methacrylate, fumaric acid esters such as ethyl fumarate and unsaturated ketones such as methyl vinyl ketone, methyl isopropenyl ketone and the like or to the polymerization of one or more active monooleflns of the vinyl type such as the foregoing nitriles, ketones and esters.

The polymerization is ordinarily effected by dispersing one part of the monomer or monomer mixture in from about one to about two parts of water containing a suitable emulsifying agent and a polymerization catalyst. A suitable polymerization modifier or promoter may also be provided in the reaction mixture if desired.

The emulsifiers employed are the alkali metal or ammonium salts of higher molecular weight fatty acids such as oleic acid, stearic acid, palmitic acid, as well as mixtures of fatty acids such as are obtained by the selective hydrogenation of tallow acids and also surface active compounds such as thealkali metal salts of sulfonic acid of fatty alcohol sulfates, for example, sodium salts of isobutylnaphthalene sulfonic acid or tetraisobutenyl sulfonic acid, sodium dodecyl sulfate and also acid addition salts of high molecular weight alkyl amines such as dodecyl amine hydrochloride or acetate. The amount of emulsifier used is ordinarily between about 0.5 to about 5 weight percent based upon the monomers used.

The catalysts which are used are substances which are capable of liberating oxygen under the conditions employed in the polymerization and include such compounds as hydrogen peroxide, benzoyl peroxide, hydrogen peroxide addition compounds, hydrogen peroxide with metal activators, tertiary butyl hydroperoxide, perborates, persulfates and organo metallic compounds such as iron carbonyl. The amount of catalyst used is ordinarily about 0.05 to about 0.6 weight per cent based upon the monomers present.

The amino compounds which may be used as polymerizationqaromoters in accordance with the present invention are water-soluble primary. secondary and tertiary amines and water-soluble derivates thereof having an ionization constant of at least about 1X The most active of these compounds are the aliphatic, alicyclic or heterocyclic amines of about 2-6 carbon atoms, such as monoethyl amine, diethyl amine, diethyl amino ethanol, piperidine and morpholine. Other amines and derivatives which may be used in accordance with this invention are methyl, propyl, butyl, amyl, hexyl, dipropyl, dibutyl, trimethyl, dimethyl-ethyl and trimethyl amines and tetraethyl ammonium hydroxide, pyrrolidine, piperazine, indole, carbozole, beta, piperidinoproplonitrile, mono-, diand triethanolamine and the methyl or ethyl ethers of dimethylor diethylamino ethanol, chloromethyl amine, chlorobutyl amine and the like. The amine promoters are preferably used in amounts of about 0.05 to about 0.5% by weight based upon the reactants.

The amine type promoters are advantageously used in combination with polymerization modifiers, particularly aliphatic mercaptans containing at least six carbon atoms such as heptyl, octyl, diisobutyl, dodecyl or lorol mercaptan' or Kimthogen polysulfides such as diisopropyl xanthogen disulflde. In lieu of the mercaptan, I may also use certain mercaptan-vinyl compound addition products such as are obtained by reacting primary, secondary or tertiary mercaptans of varying molecular weight with vinyl compounds such as acrylonitrile, methacrylonitrile, vinyl ethers. vinyl ketones and the like.

The following examples are illustrative of the present invention but it is to be understood that my invention is not limited thereto:

EXAMPLE 1 Several emulsion polymerization experiments were made in which butadiene and acrylonitrile were co'polymerized in emulsion using a persulfate-mecraptan combination in conjunction with morpholine as a promoter in accordance with the present invention. The following recipe was used:

Water -parts- 200 Soap do 4 Mercaptan C12-C14 do 0.5 Potassium persulfate do 0.3 Acrylonitrile do 26 Butadiene do 74 Morpholine -variable Reaction temperature F '77 Reaction time hours 14% Per cent conversion vs. morpholine concentration in the synthesis of acrylonitrile-butadiene copolymers Per Cent Morpho- Per Cent line Conver- (Based on sion Reactants) Similar results were obtained (i. e. conversion) after 15 /2 hours at 25 C. when 0.2% of morpholine was used as a promoter and sodium lauryl sulfate was used as the emulsifier instead of the soap.

EXAMPLE 2 Two runs were carried out in a 3-gallon stainless steel reactor equipped with intemal agitation. Each reaction charge was as given in Example 1, using a total charge of 3 kg. of monomers. One run was made using 0.4% of morpholine, while in the other run only 0.1% was used.

The results are summarized in Table 11 below from which it may be seen that the run with the larger amount of morpholine resulted in a less plastic product. Thus, although the concentration of the amine promoter is not critical from the standpoint of reaction rate. the concentration must be kept to a minimum in order to get products of good plasticity. By using larger concentrations of mercaptan modifier with the amine, it is possible to prepare polymers having Mooney viscosities as low as 50 or less.

TABLE II Mooney Viscosity Per Cent Morphollno Time, Per Cent Hours Conv.

'lom peraturc,

EXAMPLE 3 TABLE III tanusin varying amounts of piperidine. The following recipe was used:

Water parts 200 Soap 4 Mercaptan Cm-Cn 0.5 Potassium persulfate do- 0.3 Acrylonitrile 26 Butadiene 74 Piperidine variable Reaction temperature F 84 Reaction time --hr 14.75

The results of these runs are summarized-in Table V below. from which it may be seen that about 0.3% of piperidine is optimum for this reaction system.

' TABLE V Per cent conversion as. piperidz'ne concentration in the synthesis of acrylonz'trile-butadiene c0- polymers Pipcridine Per Cent on g 6 Rcactants or (l 62. 3 l). ()5 72. 5 (1. i0 77. 5 l 21) 83. 9 n, so 86. 7 0. 4o 88. 9 Q. 50 87. 2 (I. on 87. 7 1.00 88. 2

A similar accelerating effect was obtained when Copolymerizatz'on of butadiene and methyl isopropenyl ketone using piperidine as promoter I Experiment No l 2 3 4 5 6 i 7 8 Water, cc 400 400 400 400 400 400 400 401) Soap Flakes, Gms 1O 10 l0 10 10 10 10 10 Methyl Isopropenyl Ketone,

Gms 50 50 50 50 50 50 50 50 Primary Mercaptan Ore-( 1. 0 1. 0 0. 6 (l. 6 0. 6 0. G 0. 6 0. 6 l). 6 0. 6 150 150 150 150 150 150 150 150 Piperidine. cc 0. 5 5 0. 5 0.5 Reaction Time, Hrs 18% 11R} 18% 18/ 18% 18V.- 22l 22% Reaction Temp, C 40 40 40 40 40 40 40 Product, Gms 24 24 32 177 178 182. 5 79. 5 120 Conversion, Per Cent 12 12 16 88. 5 80 91. 2 39. 7 60 Plasticity of Polymer A A A A A A B A =not plastic. B=quite plastic.

EXAMPLE 4 beta piperidmopropionitnle was prepared from Similar experiments were conducted to determine the effectiveness of piperidine on the polymerization of butadiene, the data from which are contained in Table IV.

TABLE IV EXAMPLE 5 A series of runs were made preparing emulsion copolymerizates of butadiene and acrylonitrile 7 piperidine and acrylonitrile and used instead of piperidine in the synthesis of acrylonitrile-butadiene copolymers.

EXAMPLE 6 Three experiments were carried out simultaneously using the recipe as given in Example 1, except that methyl acrylate was used instead of acrylonitrile. The ratio of methyl acrylate to butacliene in the charge was 25/75. After 16 hours at 31 C., the following conversions were obtained.

Per Cent Mor- Per Cent pholine Used Conversion 7 EXAMPLE'I.

Two pressure bottle runs were made using the following recipes in order to demonstrate the efllcacy oi amine promoters in polymerization 8 It may readily be seen from this table that diethylaminoethanol, ethylamine, diethyl amine, triethyl amine, n-propyl amine and n-butyl amine gave good promoting effects. The higher systems operated at a pH below 7' 6 alkyl amines such as dibutyl amine, tributyl amine, n-octylamine and lauryl amine gave no Run A Run]; promoting effect and in some cases acted as deflnite poisons to the reaction.

Pam PM The amine promoters of the present invenwmn 400 400 10 tion are also valuable when preparing resins fi f fiflg g 2; such as polyacrylonitrile, polyacryiates, poly- Dfdtmmfismsai'aiaa 10 w methacry a e p lyvi l k tones. polyvinyl ga fi f g gz 3 2 ethers and the like from monooleflnic materials Mor;l izline....?...-: 0.0 0.2 containing a highly polar group such as a -CN,

l .15 C- or -COOR group wherein R is a lower A conversion of 34% was obtained in run A alkyl roup suc as me hy hy D D W while run B, carried out at the same temperature the like- This is clearly em tr t d by the and for the same time as run A, gave a conversion following example. of EXAMPLE 8 EXAM LE 11 A run was made in accordance with the recipe The polymerization described in Example 1 was given 1 g 3133 Z233? Tyieliififit it i' iilfiifiofifiii; mercap an e ng presen s ar run was a o at 24 C. A convers on o 0 o e eore c was obtained when neither mercaptan nor versioll} Z 3: 5 of i gg g the f;P if; if? The i 9, 5%; :22:52; d eszription 033231;; a limited 0o morp o ne u nomercap anw a converted in the same time. This run shows that g gg g the Present inventionunlike the alkali cyanides, amines iaare exgeiajlilent is Koh limi zg zg mi gzgzndg gfis t i l sgsg oter in the bsence of merca an mo ers. prom s a p since numerous variations are possible without EXAMPLE 9 departing from the scope of the following claim. A run was made in accordance with the recipe P z z' i I claim and desire o Secure y t r ven in Example 1 using 0.47 of morpholine and a 1 81 gather modified in that 0 5% of diisopropyl The process f P p rin yn hetic rubber-like xanthogen disulfide was substituted for the 0.5% materials which comprises emulsifying a mixof 512-014 melcaitag. conversiondwig (18% filter Sure ofha snajor 1proportion of it conjugateilibuta; 14 4 hours a 2 as compare ess an ene y rocar on an a m nor propor on o 40% when the diisopropyl xanthogen disulflde 40 acrylonitrile in water in the presenceof an alwas used without the morpholine promoter. kali1 metal soaipigf a high molecular wfiigtit fatty ac as emu s er, p0 ass um persu a as a EXAMPLE polymerization catalyst and an aliphatic mercap- A number of runs were made to determine the tan containing at least 6 carbon atoms, and addeiIect of several different amines upon the coing thereto 0.05 to 0.5% of piperidine. polymerization of butadiene and acrylonitrile. The recipe was the same as in example except GEORGE SW, that the amine: listed in the Table VI were used instead of morpholine. The results obtained are No references cited. summarized in the following table:

TABLI VI Promoters in the synthesis of butadiene-acrillonitrile copolilmers a ggg gg o 0.5 .15 .2 .3 .4 a .s 1.0 5 5 gg thylaminoethanol at 12 83.5 we g t-22 me il lsmffifI s4 01 24 -20I5 14y: thy] e s4. szs 90 24 -2s.s 14% N-propylamina 64 80.5 25 -23 14% Di-lsopropylamm 64 67 25 --28 14% Butylamine 50.5 'n 2 24.5-20 14% Dibuty 56.5 5s use 24.5-26 14% Tributylamine... 56.5 s1 4s 24.5-20 14 ,4 n-octylamine. 50.5 5s 25 -2s 14% Laurylamina 54 53 25 28 1 Molecular equivalent to piperidine at concentration indicated. 

